The effects of non-examples in geometrical concept acquisition

The effects of non-examples on the acquisition of the geometrical concept of semi-regular polyhedra were examined. Three treatment groups (eight examples only, four examples followed by four non-examples, four pairs, each pair consisting of an example and a closely related non-example) viewed a video-taped presentation. The criterion measure was a 20-item dichotomously-scored post-test. Results favoured the treatments containing both examples and non-examples. However, the order of presentation of the non-examples appeared to be negligible.